Recent years have seen an increased awareness of the heterogeneity among substance abusing populations. Comorbid psychopathology is one factor contributing to this heterogeneity which differentially influences treatment outcome. The bulk of research on this issue has examined adult populations, yet little is known about the influence of comorbidity in adolescent substance abusers. Available research suggests that adolescent substance abusers wit concurrent conduct disorder have poorer outcome following treatment. To address this issue, the proposed project investigates a clinical sample of adolescent substance abusers and is designed to assess differences in treatment outcome and coping skills between those with and without a comorbid diagnosis of conduct disorder. Information from this study will contribute to a better understanding of factors contributing to the poorer treatment outcome of conduct disordered adolescent substance abusers, and will provide knowledge relevant to designing more efficacious interventions. The design of this between-based cognitive-behavioral model of relapse (Marlatt & Gordon, 1985). This longitudinal study is designed to replicate and extend previous findings of the relationship between conduct disorder, treatment outcome, and the role of coping skills therein. One hundred and eighty six adolescents in treatment for substance abuse will be recruited for participation in this study. The proposed protocol compares those with and without conduct disorder on 1) drug and alcohol use status six-months posttreatment, and 2) skills for coping with relapse risk situations. Previous investigations are limited by a lack of diagnostic information on disorders other than conduct disorder. Given the high prevalence of comorbid psychopathology among clinical samples of adolescent substance abusers, the present investigation will include a diagnostic interview in order to make more precise diagnostic distinctions: substance abusing conduct disordered teens with additional diagnoses will be excluded from the conduct disorder group. The longitudinal design of this study will address two primary hypotheses: 1) Substance abusing adolescents with conduct disorder will have poorer six-month treatment outcome than teens without conduct disorder. 2) Substance abusing adolescents with conduct disorder will have poorer skills for coping with relapse risk situations than teens without conduct disorder. These deficits in coping skills will account for part of the relationship between conduct disorder and poorer treatment outcome.